1. Field of the Invention
The present invention relates to adjustable height portable tables, and, more particularly, to a portable table which can be easily raised or lowered by using a hydraulic jack.
2. Description of Related Art
Recently there has become a need to have a portable and easily adjustable table which can vary its height. For the reasons discussed below, the table must be extremely stable and, in addition, be free from any type of clutter beneath its supporting surface. Such tables can find use in various environments, such as in offices, restaurants, factories and machine shops. For example, if the table were to be used as a welding fixture to support articles as they are welded together, it would be very important for the table to have all of the above-mentioned features. Therefore, it would be important that the table be portable so that it may be moved to whatever part of the shop that the welding is to be done, the table would have to be extremely stable so that the table does not jostle, for example, when its height is being adjusted, and the table would need to be fairly clear from clutter so that various items, such as tanks for the welding equipment, can be stored underneath the table. Of particular importance, of course, is the ability for the table to adjust its height so that welding personnel can easily access various parts of equipment being worked on. Previously designs of a welding fixture were typically a fixed table which, since it could not be moved from place to place or have its height adjusted, would not be satisfactory.
Another proposed solution to the problem was to use a certain type of jack to make a welding table adjustable. Such a jack typically was simply removed, for example, from a trailer hitch and placed on a two part table so that when the jack was actuated, the table top would move up and down. This of course suffers from a major drawback in that the jack was so incredibly large that it took up all storage space under the table and tended to be of a clumsy design.
Yet another proposal to overcome the problems stated in the prior art is represented by U.S. Pat. No. 5,437,236 which discloses a multi-functional table with elevational capabilities. In that patent, there is proposed the use of a hydraulic jack between a base and a table top. This arrangement is considered to suffer two major disadvantages in that, first of all, the table is not portable and may not be easily moved from place to place in a machine shop and, more importantly, the table is not stable. While the patent does recognize its own deficiency in the table not being stable enough and does try to correct the situation by proposing using four telescoping supports as shown in FIG. 13, it is still woefully lacking in any type of frame structure which would provide the necessary support for proper welding work.
Accordingly, it is desirable to provide a portable, adjustable height table which does not suffer the drawbacks mentioned above and furthermore is easily adjustable in height, readily portable, and lacks any type of clutter below its main support surface.
The present invention includes a portable, adjustable height load bearing structure or table comprising an adjustable height table, a base frame, a slider frame assembly, a generally planar support surface and a lifting mechanism. The main portion of the base frame is formed by welding three tubular components to form an H-shape. Each of the lower end portions of the H-shape includes a mounting to support a swiveling, locking castor. Above each castor, there extends from the H-shaped main portion, a vertically extending tubular column. The slider frame assembly includes an H-shaped main portion formed of three tubular members. Four vertically extending hollow tubular column members are attached to the H-frame of the slider frame assembly, so that they may telescopingly engage the four vertically extending column members of the base frame. A generally planar support surface is attached to the top of the four vertically extending columns located on the slider frame assembly. Between the central tube of the H portion of the base frame and the central tube of the slider frame assembly, there is located a lifting mechanism, preferably a hydraulic jack. This jack can be actuated by a pedal mechanism to lift the slider frame assembly relative to the base frame. A second pedal is provided in a lifting mechanism to control the jack in order to lower the slider frame assembly at a controlled rate of descent. Additionally, an anti-sway bar is provided to prevent the lifting pump pedal from swaying when in use.
The foregoing and other novel features and advantages of the invention will be better understood upon reading the following detailed description taken in conjunction with the accompanying drawings in which like reference numerals refer to like parts in each of the figures.